Intra-uterine device



April 4, 1967 c. L. BURDICK 3,312,214

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BY 08mg April 4, 1967 CJLJBURDICK 1 INTRA-UTERINE DEVICE Filed June 6,1966 2 Sheets-Sheet 2 g m I 1/ m I v INVENTOR. Mfl/PMS mmaafia/cx UnitedStates Patent 3,312,214 lNTRA-UTERINE DEVICE Charles Lalor Burdick,Christiana Hundred, Del. (4400 Lancaster Pike, Wilmington, Del. 19805)Filed June 6, 1966, Ser. No. 555,503 10 Claims. (Cl. 128-130) Thisinvention relates to intra-uterine devices and'more particularly to anew intra-uterine device having three continuous loops.

Early in this century, Grafenberg made medical use of a simple gold orsilver ring inserted into the uterine cavity of a woman to preventpregnancies. Although generally successful, the ring fell into disreputebecause in some cases the woman experienced pain or infection, while inothers pregnancies occurred and in general the medical professioninveighed extensively against the prac tice of inserting anything intothe uterus.

After 1950, there was a resurgence of research in the field ofintra-uterine devices resulting in much greater success with fewercomplications than had been achieved by Grafenberg. Among the best knownof the present devices are the Margulies spiral, the Birnberg how, theLippes loop and various forms of rings or coils.

The types of intra-uterine devices mentioned above give pregnancy rateson large scale tests with fertile women ranging from 1.5 to or more per100 Womanyears of exposure. This compares favorably with the bestalternative methods of contraception and is, of course, much better thanno care at all.

There are, however, many deficiencies with the presently availableintra-uterine devices and some of these deficiencies are the incidenceof menstrual troubles, unusual bleeding and more seriously a high rateof spontaneous expulsion, either noticed or unnoticed. Prior deviceswhich helped alleviate the menstural trouble and unusual bleedingresulted in increased expulsion and in higher pregnancy rates.

The rate of spontaneous expulsion varies considerably between thevarious types of intra-uterine devices. The normal uterus undergoesrhythmic muscular contractions or peristalsis more or less steadily andcontinuously and of greater or less extent. The rates of expulsion willvary with this and with the degree of tightness of the cervix openingand, of course, with the design of the device itself.

Although statistical data is at present scant on the problemsencountered with intra-uterine devices, the National Committee onMaternal Health has recently compiled most of the available data intoone comprehensive compilation which appeared on page 178 of the April1966, issue of Good Housekeeping Magazine. This compilation was based ona cooperative study of forty-three medical institutions and privatepractices in the United States and Puerto Rico and involved firstinsertions and first year use in 11,222 women. The results are presentedbelow in the form of percentages per 100 woman-years of use.

Loop Spiral Bow Ring Pregnancies 2. 4 1. 8 5. 7 7. 5 Expulsions 9. 9 22.5 2. 4 18. 2 Removals 15. 6 25. 7 11. 1 10. 2 Pelvic inflammatorydisease 1. 7 3. 9 2. 2 3. 2

Percent Loop 29.6 Spiral 53.9 Bow 21.4 Ring 39.1

It can thus be appreciated that there is a need for an improvedintra-uterine device which exhibits a low pregnancy rate and yet whichminimizes the other deficiencies set out above.

Up to the present time there have been no systematic studies of ways toconform intra-uterine devices to the contours of a human uterine cavity.It would seem that the design characteristics of such devices shouldtake into consideration a knowledge of the uterine morphology.

As pointed out by Davis and Israel in Uterine Cavity Measurements inRelation to Design of Intra-Uterine Contraceptive Devices,"Infra-Uterine Conception, Proceedings of the Second InternationalConference, October 1964, New York City, at page 135, An idealintrauterine device should combine two mechanically contradictorycharacteristics: ease of insertion and resistance to expulsion. None ofthe intra-uterine devices currently in use completely satisfy thesecriteria. In addition, little attention has been given to designelements to take advantage of uterine musculature and peristalsis and tofacilitate the downward passage of the ovum with minimum contact withthe uterine cavity walls. The conventional design of a loop sets up anactual series of barriers tending to impede a fertilized ovums downwardtransit toward the cervical exit.

According to this invention, there is provided an intrauterine devicegenerally in the shapeof a trefoil which comprises an inert endlessmaterial in the shape of three continuous freely-movableadjacently-positioned loops; the loops being inter-connected in such amanner that the two terminating portions of each loop continue smoothlyinto the terminating portions of the adjacent loops. The intra-uterinedevice is capable of being deformed by the application of a small amountof force and yet is sufliciently elastic to return substantially to itsoriginal shape when the force is removed.

The term freely-moving, as used in this specification, means that whenthe device is held in a horizontal position, each loop is independentlycapable of motion in a vertical, horizontal, or rotary direction, or inany combination of these. The term adjacently-positioned means that eachloop is adjacent to both of the other loops.

A method of preventing pregnancy using an intrauterine device asdescribed above comprises the following steps:

(1) Deforming and inserting this intra-uterine device into the open endof a cannula which can be passed through the cervical canal,

(2) Inserting the open end of, the cannula through the cervical canalinto the uterine cavity, and

(3) Expelling the intra-uterine device from the cannula into the uterinecavity whereby the intra-uterine device returns substantially to itsoriginal shape and becomes lodged within the uterine cavity.

The intra-uterine device of this invention has the advantage of havingno free ends or cuspate forms which tend to pierce the delicate uterinewall upon insertion of the prior devices or upon the prior devicesshifting position after insertion. Another advantage is that thegeometrical design of the new intra-uterine device makes it far lesssusceptible to expulsion from the uterus. A still further advantage liesin the continuous shape of this intra-uterine device which makes it farmore adaptable to the uterine cavity than the prior art devices. A,still further advantage of this device is that the three loops provideready channels for unimpeded transit of the ovum or blastocyst throughthe main uterine cavity toward the cervical exit. A still furtheradvantage lies in the ease of forming the intra-uterine device of thisinvention in a variety of sizes and shapes within the basicconfiguration of three continuous loops which makes it readily adaptableto insertion in a wide range of uterine cavities.

The invention will be better understood by reference to the drawings.

FIGURE 1 is a plan view of inert endless material in the shape of anannulus suitable for forming into the intra-uterine device of thisinvention.

FIGURE 2 is a perspective view of a template with three mandrelssuitable for forming the intra-uterine device of this invention.

FIGURES 3 through 8 are plan views of some of the varieties of theintra-uterine device of this invention.

FIGURE 9 is a plan view of a cannula suitable for inserting theintra-uterine device of this invention.

FIGURE 10 is a plan view showing how the intrauterine device of thisinvention is inserted.

FIGURE 11 is a plan view of a human uterus and cervical canal with anintra-uterine device of this invention properly lodged in the uterinecavity.

FIGURE 12 is a cross-sectional view of an intrauterine device of thisinvention lodged within the uterine cavity.

As can be seen from FIGURES 3 through 8, the trefoil intra-uterinedevice of this invention can have a variety of shapes and sizes. Thegeometrical feature characteristic of all of the shapes is that each hasthree continuous loops and no free ends. Within the basic configuration,it is possible to have species of the trefoil intra-uterine devicewherein all of the loops are crossed, none of the loops are crossed, orwherein any combination of crossed loops and uncrossed loops in betweenthese limits is present. For example, FIG. 3 illustrates an embodimentwith three crossed loops, FIG. 6 illustrates an embodiment with the twoupper loops crossed and a lower loop which is uncrossed, and FIG. 8illustrates an embodiment with two upper uncrossed loops and a lowercrossed loop.

The intra-uterine device of this invention can be manufactured bystarting with an inert endless material approximately circular incross-section in the form of an annulus 2 as is shown in FIGURE 1. Theannulus is fitted to the template by bending and twisting it around themandrels 12 until the desired shape is obtained. The .inert material isheat set on the template so that it will retain its shape after removalfrom the mandrels. Heat setting is achieved by heating the material toan elevated temperature below the melting point and then allowing thematerial to cool to room temperature. It is sometimes desirable toattach a tail 4 to the ring so that when the device is in place in theuterine cavity, the tail extends into the womans vagina and she cancheck to see that the device is still in place by feeling for the tail.A tall can be made from any type of flaccid, strong, inert filament suchas nylon or linear polyethylene.

Any inert endless material can be used for this intrauterine deviceprovided it is physiologically inert and provided it is capable of beingdeformed by the application of a small amount of force and yet issufliciently elastic to allow the intra-uterine device to returnsubstantially to its original shape when the force is removed. Thedevice only returns substantially to its original shape because itadapts itself to the configuration of the uterine cavity therebycausing, in some cases, small deformation of the device. By a smallamount of force is meant the amount of force which a person can exert bysqueezing his thumb and forefinger together. When this force is exertedon the intra-uterine device, the device is pinched into a flat,double-looped shape 52 which is easily insertable into the flexible endof the cannula 44 of FIGURE 9. Prior threading of the tail 4 through thecannula, or a separate thread looped through the device, can assistmaterially in drawing the device into the cannula.

Another helpful means for this is that tail 4, in addition to beingfastened at point 27, may have a suitable extension which connects withthe cross member between loops 30 and 32. This extension may providealso an additional channel facilitating exit of the ovum from theuterus.

The inert endless material can be a single filament or multifilament.Any physiologically inert material having the required elasticity issuitable and some useful examples include polymers of propylene,ethylene, tetrafluoroethylene, acrylic acid, methacrylic acid,terephthalic acid, and esters of acrylic, methacrylic, and terephthalicacids, acrylonitrile, methacrylonitrile, vinyl acetate, butadiene,styrene and interpolymers of these. Other useful materials include anyof the well known polyamide compounds such as poly(caproamide)poly(metaphenylene isophthalamide), poly(hexamethylene sebacamide), andpoly(hexamethylene) ,adipamide. Natural substances which meet theinertness and elasticity standards such as cat gut and silk worm gut areuseful. Silicone rubbers are also useful.

A radiation opaque material such as barium sulfate can be added to theinert endless material to make possible the determination by radiologyof the exact location of the intra-uterine device after insertion.

The cross-section of the inert annular material is not subject to beingdefined in terms of exact dimensions. In general, it depends upon themodulus of the material used. There are other factors to be considered,of course,

in selecting a material of proper cross-section and one of these is thethickness of the device desired which again depends upon the uterinedimensions and size of the cervical opening. For the normal parousuterus, one would usually use a device measuring about 32 millimetersacross outside-to-outside of the upper loops and about 30 millimetersoutside-to-outside from top to bottom. The cross-section of the inertendless material itself can range from about 0.7 to 2.20 millimeters indiameter, or, if of multifilament, can be conveniently made of ten totwelve turns of a filament of about 0.2 to 0.5 millimeter in diameter.When the inert endless material is not exactly circular in shape, thesediameter measurements apply to the major diameter.

A convenient shape for the cross-section of the inert endless materialis approximately circular. The term approximately circular is meant toinclude for purposes of this invention shapes which are circular,elliptical, oval or any other cross-sectional shape which is bounded bysmooth simple closed curves. Any cross-sectional shape, however, issufficient.

In general, the interior shape of a human parous uterus 20 can best bedescribed as a flattened cavity with upper and lower walls or foldssubstantially in contact with each other and with edges approximating anisoceles triangle standing upon its apex with the two uterine horns 23and 25 located at the opposite ends of the base. As is shown in FIGURES10 and 11, the three looped intrauterine device of this invention has anatural form to approximate this shape thereby filling almost entirelythe uterine cavity 21. Although it is not known exactly howintra-uterine devices prevent pregnancy, the general belief is thatfilling a greater percentage of the uterine cavity will produce betterresults.

As has already been pointed out, the uterine cavity is normally fiat.With the three looped intra-uterine device of this invention, apreferred separation of the uterine cavity walls can be achieved byselecting an inert endless material of proper diameter and then byfabricating the loops in any of the previously described variations togive a proper separation between the anterior 22 and posterior 24 wallsof the uterus without stretching the uterus itself to an extent whichwould be painful to the woman.

As has already been pointed out, peristalsis, the continual contractionand expansion of the fundus muscle located at the top of the humanuterus 26 is synchrony with the other musculature is a main cause of theexpulsion of the present intra-uterine devices. As can be seen fromFIGURE 11, the upper configuration of the three looped intra-uterinedevice has opposite loops 30 and 32 connected across by a depressedflexible curvature 28 which gives little opportunity for the heavymusculature in the central portion of the upper uterine wall to pressdownward against the device. What appears to happen is that theresultant of the forces tends to push the two upper loops of the devicefurther into their corresponding uterine horn cavities and to expand thelower loop 27 horizontally, all of whichtends to resist expulsion and tohold the device in place. An important feature of this device, then, isthat the lower loop 27 be broad enough at its base to resist theinitiation of expulsion due to this peristalsis or to any otherundesired expelling force.

The preferred embodiment of the invention is a three loopedintra-uterine device which is constructed from polyethylene mixed with aradiation opaque material. An intra-uterine device constructed withpolyethylene of an appropriate diameter can be deformed with a smallamount of force and yet is elastic enough to return to its originalconfiguration within a short period of time after the force is removed.Polyethylene is also a material which has been well tested for use inintra-uterine devices and found to be inert. As previously specified,the radiation opaque material makes it possible to determine by themethods of radiology the exact location of the device after it has beeninserted.

The three looped intra-uterine device of this invention is insertedthrough the cervix into the uterine cavity by the standard techniquewhich employs a thin-Walled cannula as shown in FIGURE 9. The cannulahas a rigid tubular body 42 with a flexible tubular end portion 44 and apush rod 46.

For a typical insertion, the attached tail 4 of the device is threadedthrough the cannula from the uterine end and the three loopedintra-uterine device 52 is pinched together and inserted into theflexilble end portion 44 of the cannula and the push rod is insertedthrough the other end as shown in FIGURE 9. Unless assembled underaseptic conditions an appropriate aqueous or gaseous sterilization isnow made.

The cannula is then inserted through the cervical canal 54 of the womanand into the bottom of the uterus 56 as shown in FIGURE 10. The push rod46 is pushed manually and gently axially frontwards thereby forcing theintra-uterine device 52, shown partially expelled, from the flexible endportion 44 and into the uterine cavity 21 where the device returns toapproximately its original shape as shown in FIGURE 11. The push rod andcannula are withdrawn leaving only the tail extending through the cervixinto the vagina.

If it is desirable, the cannula 42 can have one or more flanges attachedto it which can be movable or fixed as desired to aid the physician ininserting the cannula to a proper depth and orientation within theuterine cavity.

Although only a hand or laboratory method for manufacturing theseintra-uterine devices has been described, it is clear that any othertechniques such as injection molding or machine fabrication is suitable.The laboratory method enables the device to be tailored to any desirableset of dimensions and this is an important feature. The laboratorymethod also allows the fabrication of various shaped devices stillhaving the basic configuration of three loops. For instance, themandrels 12 can be set vertically wit-h respect to the plane of thetemplate 10, or at various other angles. The latter gives a sequentialangular arrangement having a final shape with the loops angled to theplane of the device somewhat like a ships propeller.

A simple annulus of the inert endless material 2 has been shown to beuseful as a starting material in the fabrication of these intra-uterinedevices, but there can be many other useful modifications of this. Forinstance, it might be desirable to use a double-looped ring of the inertendless material to start with. The choice of starting material withinthe limits already described is left to the fabricator who is in aposition to best know which initial shape will be easiest to manipulateinto the final desired shape.

The inert endless material can be treated in any way which will notdestroy its inertness or elastic qualities to aid in detecting whetherit is in correct position or not. The addition of barium sulfate to makeit radiation opaque has been described but many other techniques can beenvisioned. One alternate method would be to use a material electricallyconductive in nature whereby its presence could be substantiated quicklyby an electric induction measuring instrument placed on the lowerabdomen.

The ultra-uterine device of this invention is useful for preventingpregnancies in women.

One advantage which this device has over those of the prior art is itsgeometrical con-figuration. The three loops are designed to obtainmaximum filling of the uterine void while exposing a minimum of thedevice to the pushing effect of the fundus muscle thereby resulting in agreater resistance to expulsion than any of the prior art devices. Thethree loop configuration additionally imposes minimum barrier action tothe transit of the ovum through the uterine cavity. The free channelsoffered to the passage of the ovum give it minimum opportunity forcontact with the uterine walls thereby resulting in a much lesserlikelihood of implantation upon the uterine walls.

Another advantage over the prior art is the smooth, continuous nature ofthis in-tra-uterine device. The elimination of any free ends or anyblunt or cuspate forms makes this device much less likely to pierce thedelicate uterine walls either upon insertion, removal or while thedevice is in place. It is essential that the intra-uterine device ofthis invention be fabricated from a material which has no free endsinitially. The free ends make a device much more likely to pierce theuterine walls and this problem is not eliminated by binding or tying thefree ends together because this necessarily results in a 'blunt orcuspate form exactly in contradistinction to the smooth, continuousnature which is desirable and which is achieved by the intra-uterinedevices of this invention.

The devices of this invention are also more adaptable to a variety ofuterine cavity shapes and dimensions than prior art devices because oftheir smooth, continuous nature and because of the geometricalconfiguration of three loops. Each of the three loops is free-movingwith respect to the other loops giving the whole device great degree offlexibility. The smooth, continuous nature of the device allows it tofind and gently press against the uterine walls without damaging orirritating them.

This device has a further advantage over the prior art in that it canreadily and easily be formed in a variety of sizes and shapes within thebasic configuration of three continuous loops which makes it readilyadaptable to insertion in a wide range of uterine cavities.

What is claimed is:

1. A trefoil intra-uterine device which comprises an inert endlessmaterial in the shape of three continuous freely movableadjacently-positioned loops said loops being interconnected such thatthe two terminating portions of each loop continue smoothly into theterminating portions of the adjacent loops, said intra-uterine devicecapable of being deformed by the application of a small amount of forceand being sufficiently elastic to return substantially to its originalshape when the force is removed.

2. The intra-uterine device of claim 1 wherein the inert endlessmaterial comprises a polymer selected from the group consisting ofpolyamides, polyolefins and polyesters.

3. The int-ra-uterine device of claim 1 wherein the three continuousloops lie substantially within one plane.

4. The intra-uterine device of claim 3 wherein the inert endlessmaterial comprises a polymer selected from the group consisting ofpolyamides, polyolefins and polyesters.

5. The intra-uterine device of claim 3 wherein the inert endlessmaterial comprises a polymer of a compound selected from the groupconsisting of ethylene, propylene, tetrafluoroethylene, hexamethyleneadip amide, acrylic acid, methaorylic acid, terepht-halic acid, andesters of acrylic, methacrylic and terephthalic acids.

6. The intra-uterine device of claim 3 wherein the inert endlessmaterial comprises a polymer of ethylene having a cross-sectionaldiameter of from about 0.70 millimeter to about 2.20 millimeters. V

7. The intra-uterine device of claim 3 wherein the inert endlessmaterial comprises a multifilament of a polymer selected from the groupconsisting of polyamides, polyolefins and polyesters.

8 8. The intra-uterine device of claim 1 wherein all three of the loopsare crossed.

9. The intra-uterine device of claim 1 wherein two of the loops arecrossed and one of the loops is uncrossed. 10. The int-ra-uterine deviceof claim 1 wherein one of the loops is crossed and two of the loops areuncrossed.

References Cited by the Examiner UNITED STATES PATENTS 2,122,579 7/1938Meckstroth 128-130 2,176,559 10/ 1939 Meckstroth 1'2-8l30 3,077,8792/1963 Knoch 1'28l30 3,200,815 10/1 965 Margulies 128l30 3,250,2715/1966 Lippes 1-28-130 3,253,590 5/ 1-966 Biirnberg et al. 128130 ADELEM. EAGER, Primary Examiner.

1. A TREFOIL INTRA-UTERINE DEVICE WHICH COMPRISES AN INERT ENDLESSMATERIAL IN THE SHAPE OF THREE CONTINUOUS FREELY MOVABLEADJACENTLY-POSITIONED LOOPS SAID LOOPS BEING INTERCONNECTED SUCH THATTHE TWO TERMINATING PORTIONS OF EACH LOOP CONTINUE SMOOTHLY INTO THETERMINATING PORTIONS OF THE ADJACENT LOOPS, SAID INTRA-UTERINE DEVICECAPABLE OF BEING DEFORMED BY THE APPLICATION OF A SMALL AMOUNT OF FORCEAND BEING SUFFICIENTLY ELASTIC TO RETURN SUBSTANTIALLY TO ITS ORIGINALSHAPE WHEN THE FORCE IS REMOVED.